This invention has to do with an improved cutting mechanism for pole pruners. In the art of caring for trees and plants that grow to substantial height, it is desirable that the trees and plants be pruned or trimmed to remove undesirable foliage and to control growth.
When trimming of trees and other tall plants, to reduce the number of incidents where persons must climb into trees or climb ladders and the like to effect trimming the upper reaches of the trees and plants, the prior art provides pole pruners consisting of elongate, normally vertically extending, manually engageable poles with cutting mechanisms at their upper ends.
The cutting mechanisms are normally operated by pull cords that extend to the lower ends of the poles where they can be engaged by the persons operating the pole pruners. The cutting mechanisms for pole pruners commonly include elongate, vertically extending heads with lower mounting portions connected with the upper ends of their related poles, shank portions projecting upwardly from the mounting portions and hook portions extending upwardly, radially forwardly and thence downwardly relative to the shank portions and defining downwardly and laterally opening work-receiving hook openings. The portions of the heads defining the hook openings have flat side surfaces which cooperate with inside edges of the hook openings to define inwardly disposed shearing edges. The mechanisms next include flat, elongate, normally vertically extending blades positioned adjacent the above noted flat surfaces of the heads. The upper ends of the blades are pivotally mounted on the heads adjacent the shank portions and rearward of the lower portion of the hook openings and pivot forwardly and upwardy across the hook openings and said shearing edges when actuated. The upper ends of the blades have upwardly and rearwardly projecting levers with upper rear ends connected with force applying actuating means which are manually operable at the lower ends of the poles. Rearward and downward pivoting of the levers by operation of the actuating means pivot the cutting blades forwardly and upwardly from their normal positions to their actuated positions.
Finally, most pole pruners include spring means to normally yieldingly maintain the blades in their normal positions and to yieldingly return the blades to their normal positions subsequent to their being actuated.
In use, the hooks of pole pruner cutting mechanisms are engaged over the branches of trees or plants to be cut and their blades are pivoted forwardly and upwardly across the hook openings, cutting the branches engaged therein (by operation of the actuating means). Thereafter, the blades are returned to their normal postion by the spring means, preparatory to engaging the hooks with the next to be cut branches.
While pole pruners of the character referred to above have been used successively for a great number of years and while changes in the design of the cutting mechanisms therefor have been made to enhance their performance and usefulness, there is an inherent tendency for the blades of such mechanisms to displace branches downwardly and outwardly from engagement within the hook openings when and as the blades are pivoted from their normal positions into engagement with branches engaged therein, before the blades are fully actuated. The above noted displacement of branches is often called "kicking out" and becomes more common and a greater problem as the size (diameter) of branches being worked upon increases and/or as the hardness of the wood of the branches increases.